Smoke generator and method of controlling a smoke generation

ABSTRACT

The invention relates to a method of controlling a smoke generator. The smoke generator is adapted to be connected to a supply of a pressurized gas and a supply of a smoke fluid and further comprises a valve to regulate the pressure of the gas, a fluid driving means, a mixing unit for mixing the smoke fluid and the gas, and a heat exchanger heating the mixture of the pressurized gas and the smoke fluid to vaporize the smoke fluid and form a smoke upon ejection into surrounding air. The control method according to the invention then comprises the steps of receiving a smoke density parameter indicative of a desired amount of smoke to be generated by the smoke generator, measuring a gas pressure at a position between the valve and the heat exchanger, and using these parameters in controlling the valve. 
     The invention further relates to a smoke generator arranged for performing the control method.

FIELD OF THE INVENTION

The present invention relates to a method of controlling a smoke generator wherein the smoke generator drives a mixture of a smoke fluid and a pressurized gas into a heat exchanger to vaporize the smoke fluid and form a smoke upon ejection into surrounding air. The invention further relates to a smoke generator adapted for performing the control method.

BACKGROUND

Smoke and fog generators are used in a variety of applications such as in security applications, for simulating fire as a training aid, or in entertainment, e.g. for creating special effects or lighting effects on stage. In the entertainment the smoke or haze created by smoke generators are especially important for the smoke effect but also essential in creating lighting and lighting effects, where some lightings effects like mid-air light beam effects only become visible when used together with a fine diffused haze.

A smoke generator in general works by a smoke fluid being driven into a heat exchanger to vaporize. When ejected into the ambient, the vaporized smoke fluid condensate and forms a smoke. Different types of smoke or fog generators exist capable of creating everything from a thick heavy smoke or fog to the finest barely visible haze.

Here and in the following the term ‘smoke’ and ‘smoke generators’ will be used in general to describe both smoke, fog and haze, and a generator for creating a smoke, fog, or haze effect. Likewise, the term ‘smoke fluid’ is here and in the following used as a general term for a fluid, which after vaporization and subsequent condensation to micro droplets forms a smoke.

The quality or characteristics of the generated smoke depends in particular on the type of smoke fluid used, which then yields different requirements to the temperatures needed to vaporize the fluid, to the applicable heat exchanger design, and to the means for ensuring a sufficient smoke fluid flow into the heat exchanger.

Different types of smoke generators exist with different means for driving the smoke fluid into the heat exchanger, such as a simple air pump, or mixing the the smoke fluid with a compressed or pressurized gas, or pressurizing the smoke fluid itself. It is important to drive the smoke fluid continuously into the heat exchanger under sufficient high pressure to ensure a complete vaporization and to create the fluid flow necessary to create the desired amount of smoke.

It is known to use a constant externally applied pressure from a gas cylinder, which upon connection to the system is throttled down through e.g. a metering orifice to provide the desired flow to the heat exchanger. In most applications, the gas flow is manually controlled to allow some variation in output. However, such generators often encounter problems of variations in output, as the pressure in the gas cylinder reduces.

Also, the flow through the heat exchanger can be seen to be unsteady due to the backpressure created by the vaporisation process of the smoke fluid. This leads to variability in the flow through the unit which is then perceived as variability in the output making the resulting haze uneven, and reducing the quality of the effect when seen with normal stage lighting. The problem of uneven smoke generation is seen to increase with increased smoke fluid delivery, i.e. with more dense smoke generation. The problem may to some extent be alleviated by using a gas supply of sufficiently high pressure at all times which however is economically and environmentally undesirable.

DESCRIPTION OF THE INVENTION

It is an object of embodiments of the invention to provide a method of controlling a smoke generator avoiding some of the above mentioned problems such as to provide a more even smoke output of the generator.

A further object is to provide a smoke generator which can operate with a reduced gas and energy consumption, and which is more environmentally friendly.

A further object is to provide a method of controlling a smoke generator capable of producing a stable and controllable smoke with a desired force and density or volume for all levels of smoke generation.

A further object is to provide a method of controlling a smoke generator providing enhanced safety and control of the pressure level of the supplied gas.

In accordance with the invention this is obtained by a method of controlling a smoke generator wherein the smoke generator is adapted to be connected to a supply of a pressurized gas and a supply of a smoke fluid and wherein the generator comprises a valve to regulate the pressure of the gas, a fluid driving means to regulate the flow of the smoke fluid, a mixing unit arranged to mix the smoke fluid and the pressurized gas, and a heat exchanger to heat the mixture of the pressurized gas and the smoke fluid to vaporize the smoke fluid and form a smoke upon ejection into surrounding air. The method according to the invention comprises the steps of receiving a smoke density parameter indicative of a desired amount of smoke to be generated by the smoke generator, regulating the flow of the smoke fluid as a function of the smoke density parameter, measuring a gas pressure at a position between the valve and the heat exchanger, and controlling the valve as a function of the smoke density parameter and the measured gas pressure.

Generally speaking and traditionally, during operation a smoke from a smoke generator can be modified in two different ways separately or at the same time: by adjusting the airflow or outflow of the smoke and by adjusting the amount or the density of the smoke. The airflow is typically adjusted and controlled by adjusting a fan at the exit of the generator blowing the smoke out of the generator, whereas the amount of smoke to be generated is changed by reducing or increasing the amount of smoke fluid sent through the heat exchanger and vaporized.

By the invention above is obtained that the gas pressure is regulated and controlled as a function of the smoke density parameter. Hereby is obtained a gas pressure at the entry of the heat exchanger corresponding to the desired amount of smoke and thereby to the flow of smoke fluid being driven to the heat exchanger.

At the same time by controlling the valve as a function of the gas pressure measured at a position between the valve and the heat exchanger is obtained a feedback control loop whereby may be obtained a desired target pressure at all times for any flow of smoke fluid being driven to the heat exchanger and for a gas supply at any pressure.

Hereby is further obviated the problem of existing systems of back pressure in the heat exchanger causing the fluid flow through the heat exchanger to fluctuate and the smoke generation to be uneven. The control method according to the above thereby advantageously provides a smoothness of the smoke output of the generator and a more even and steady smoke generation. This greatly affects and improves the light effects which can be realized when smoke generators are used to make the light visible.

The control method according to the invention further acts to automatically reduce the gas consumption especially at low smoke outputs where the smoke fluid flow is lower and the required pressure therefore correspondingly lower. Hereby, the overall consumable cost may be lowered correspondingly. Experiments have shown that for lower smoke outputs the gas consumption can be reduced down to one third or less the normal consumption without the use of the control method. The reduced gas consumption also makes the smoke generator with the proposed control method more environmentally friendly.

As the gas pressure is controlled as a function of the measured gas pressure is furthermore obtained the desired target pressure is obtained automatically independent of any reduction or irregularities in the pressure of supplied gas as may for example occur when the volume in a gas cylinder is reduced.

Also, the desired target pressure is realized irrespective if a gas valve on the gas supply is correctly set by user, which is otherwise a common problem causing the smoke generator to function non-optimally.

The smoke generator is adapted to be connected to a supply of a pressurized gas, which may be any gas compatible with the type of smoke fluid. This may for example be a gas supplied from a gas cylinder, from a simple air pump, or from a gas generator such as a Nitrogen generator using selective adsorption. The pressurized gas may for example be air, Argon, Nitrogen, CO2, other inert gasses, or combinations hereof.

The gas is pressurized such as to aid in driving the smoke fluid to and through the heat exchanger. The pressure of the gas may be initially throttled down upon entry to the smoke generator to adjust the pressure level from the gas source to the pressure level applicable by the smoke generator. Such initial gas pressure regulation may be manually operated.

The valve is controlled to obtain a desired target pressure. The target pressure in general depends on different parameters such as the type of the smoke fluid, the type and design of the heat exchanger and the temperatures at which it is operated and as required to vaporize the smoke fluid. Some types of heat exchangers require a higher level of pressure to drive the smoke fluid through the heat exchanger. Most importantly, the desired target pressure depends on the smoke fluid flow in that a higher pressure at the entry of the heat exchanger is required to ensure a higher flow and a steady constant flow through the heat exchanger. This dependence is reflected in the pressure valve being controlled as a function of a received smoke density parameter indicative of a desired amount of smoke to be generated by the smoke generator. If the desired amount of smoke is increased, the smoke fluid flow and the desired target pressure are increased correspondingly. Therefore the pressure valve is advantageously controlled as a function of the received smoke density parameter.

The smoke fluid may be oil based or water based, such as for example a water based glycerine or a glycol.

The fluid driving means to regulate the flow of the smoke fluid may comprise a pump of some type such as an air or liquid pump, diaphragm pump, piston pump, or a dosage pump. The fluid driving means may alternatively comprise a gas pressurizing the fluid.

The valve for regulating the pressure of the gas may advantageously be a proportional valve such as for example an Emerson proportional valve, a disk valve, or a solenoid valve. In an embodiment the control of the valve is provided completely or in part by the electronics in the smoke generator. The control signals controlling the valve can be based on any kind of signals, for instance PWM, DC signals, Frequency and/or amplitude modulated AC signals or digital signals.

The mixing unit arranged to mix the smoke fluid and the pressurized gas may simply comprise a T-branch connection or a mixing chamber. The mixing of the smoke fluid and the gas may be performed after or before the valve regulating the pressure. If the mixing unit is placed after the valve such that the gas and the smoke fluid is mixed after the gas pressure has been regulated is obtained that the requirements to the pressure capability of the fluid driving means are less high.

The heat exchanger may comprise any heating exchanger for heating a fluid-gas mixture as known in the art. The heating exchanger may in one embodiment comprise a heating block with a heating element placed in a heat storage. The control method according to the invention is further advantageous in making it possible to operate and control the smoke generator at relatively low pressures. This opens up for the possibility to use different types of heat exchangers which may have a lower risk of blockage beside the clear advantage of reducing the gas usage.

The smoke density parameter is a parameter indicative of a desired amount of smoke to be generated by the smoke generator and may be communicated as input to the control unit based on an external communication signal e.g., based on a DMX 512, Art-Net or RDM protocols as known for entertainment lighting. However any communication protocols/means can be uses such as Ethernet based protocols, DMX protocol, or the like, or may additionally or alternatively be based on a pre-programmed pattern stored in the control unit.

The gas pressure is measured by a pressure sensor placed at a position between the valve and the heat exchanger. The pressure sensor may comprise a capillary tube to restrict the flow to the sensor. The pressure sensor may use piezo-resistive elements to decrease the response time of the sensor and increase the performance of the control method. The pressure sensor may comprise a diaphragm type sensor, a capacitive sensor, and/or a MEMS device.

The pressure sensor may advantageously be placed as close to the heat exchanger as possible thereby obtaining a better control of the pressure at the entry of the heat exchanger. The pressure sensor may in an embodiment be placed in the conduit before the gas is mixed with the smoke fluid. Hereby more low cost sensors with limitations on temperature and moisture can be used.

The position of the pressure sensor before or after the mixing with fluid and its distance to the entrance of the heat exchanger further affects the desired target pressure to be obtained by the regulation of the valve according to the control method of the invention. This on the other hand means that a smoke generator can perform equally well for different locations of a pressure sensor only by adjusting how the valve is regulated as a function of the measured pressure accordingly.

The regulation of the smoke fluid flow and the regulation of the pressure valve may be performed by the same or by different control unit.

In an embodiment of the invention the step of controlling the valve is performed as a PI or a PID control. The control of the valve may be implemented as a closed loop control for example by a standard PI or PID control algorithm. In an embodiment a simple PI control may be adequate for the precision required in the system. Compensation may in one embodiment be provided by making a dominant pole at a frequency at least a decade below any others in the system. By a PI or PID control may be obtained a simple yet effective, fast, and robust control and regulation of the pressure valve. The valve is hereby controlled to continuously obtain a desired target pressure value and which is set in dependence of the desired amount of smoke and therefore set to fit the expected smoke fluid flow.

In an embodiment the pressure is measured before the mixing with smoke fluid. As mentioned previously the environmental conditions to be sustained

In a further embodiment, the step of measuring the gas pressure comprises measuring the pressure after the fluid is mixed with the gas. Hereby may be used a pressure sensor without a need for restricting the flow to the sensor, which may help to reduce the response time of the sensor improving the performance of the control system.

According to further embodiment of the invention, the method further comprises determining a flow of the smoke fluid and regulating the flow of the smoke fluid as a function of the smoke density parameter and the smoke fluid flow. Hereby is obtained that the flow of the smoke fluid is regulated not only according to the smoke density parameter, but also according the actual flow of the smoke fluid. Hereby may be obtained a more precise regulation of the smoke fluid and accordingly of the amount of generated smoke.

In yet a further embodiment, the method further comprises determining a flow of the smoke fluid and controlling the valve as a function of the smoke density parameter, the smoke fluid flow and the measured gas pressure. Hereby is ensured that the valve and thereby the pressure is adjusted according to the actual flow of smoke fluid in the generator. In this way is obtained a more precise control as the smoke fluid flow is not merely assumed correctly adjusted according to the smoke density parameter. Also, the method then ensures a precise valve setting and thereby pressure irrespective of any imprecise or fluctuating regulation of the smoke fluid flow. Further, this is advantageous in the method then can detect if the smoke fluid flow is unexpectedly high or low or interrupted, and control the generator accordingly for example by emitting an error signal, ensuring the generator is purged or shut down. Hereby the safety of the system and the smoke generator is greatly increased. Such irregular or unexpected smoke fluid could be caused by for example a malfunction of a part of the smoke generator, an unexpected stop of the fluid driving means or simply because the smoke fluid is supply is emptying. By the purging is ensured that any progressive build-up of polymerized glycol in the smoke generator can be avoided. The shutdown process would thus prevent further damage of the smoke generator upon malfunctioning of one part of the system, reducing any service expenses, and limiting the damage to the machine.

In an embodiment, the smoke fluid flow is determined by means of a flow sensor. The flow sensor may be positioned anywhere between the fluid supply and the mixing unit.

In an embodiment the fluid driving means comprises a dosage pump and the smoke fluid flow is determined from the operating of the dosage pump. Hereby the fluid flow can be simply determined without the need of a flow sensor as the fluid flow is given by the number of pulses applied to the drive circuits of the dosage pump within a given time.

In an embodiment the method further comprises determining a temperature of the heat exchanger and controlling the valve as a function of the temperature of the heat exchanger. Hereby is obtained that the valve and thereby the pressure is adjusted to yield optimal values corresponding to the actual temperature of the heat exchanger such that the desired vaporisation in the heat exchanger can be realized. Hereby the control unit may also advantageously detect any malfunction of the heat exchanger and control the valve and the optionally the smoke fluid supply accordingly. In this way the control unit may for example initiate purging of the heat exchanger and/or shut the generator down in the event of an unexpected temperature of the heat exchanger.

In an embodiment of the invention, the method further comprises receiving information on the type of the smoke fluid and controlling the valve as a function of the smoke fluid type. This allows the smoke generator to be able to operate with different types of smoke fluid as the settings for the valve and thereby for the target pressure at the entry to the heat exchanger can be simply adjusted accordingly and based on the received information. Hereby the problems of the user using a different smoke fluid than intended otherwise leading to less optimal smoke generation may be obviated or reduced. In an embodiment the user may be given the possibility to choose between the different types of smoke fluid and indicate the choice to the generator which will then operate correspondingly.

In an embodiment of the invention, the control is performed by means of a look-up table comprising values of target gas pressure for a number of smoke density parameters. Hereby the control may perform a closed loop operation continuously regulating the valve to obtain the target pressure value as given by the look-up table. As also mentioned previously the target pressure may in addition to depend on the smoke density parameter depend on parameters such as the type of the smoke fluid, the position of the pressure sensor, the smoke fluid flow, the temperature of the heat exchanger, the fan settings, and/or the humidity and temperature of the surroundings.

According to a further aspect the invention relates to a smoke generator adapted to be connected to a supply of a pressurized gas and a supply of a smoke fluid. The generator comprises a valve arranged to regulate the pressure of the gas, a fluid driving means to regulate the flow of the smoke fluid, a mixing unit arranged to mix the smoke fluid and the gas, a heat exchanger arranged to heat the mixture of smoke fluid and the gas to vaporize the smoke fluid and form a smoke upon ejection into surrounding air. The generator further comprises a pressure sensor arranged to measure the gas pressure at a position between the valve and the heat exchanger, and a control unit adapted to receive a smoke density parameter indicative of a desired amount of smoke to be generated by the smoke generator. The control unit is further adapted to regulate the flow of the smoke fluid as a function of the smoke density parameter, and to control the valve based on the smoke density parameter and the measured gas pressure. The advantages hereof are as discussed in relation to the first aspect of the invention of a method of controlling a smoke generator.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following different embodiments of the invention will be described with reference to the drawings, wherein:

FIG. 1 illustrates a smoke generator comprising a control unit for controlling the generator according to one embodiment of the invention,

FIG. 2-4 show different embodiments of a smoke generator according to the invention, and

FIG. 5 is a flow chart showing an embodiment of the control of the smoke generator.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a smoke generating system 100 comprising a smoke generator 101 according to an embodiment of the invention connected to a supply of smoke fluid 103 and a supply of a pressurized gas 107. In one embodiment, the gas pressure is throttled down by means of a valve 109, which may be manually operated. This valve may be omitted. This valve 109 may further comprise an internal F/B indicating regulator, 120, for enhanced safety and control of the pressure level of the supplied gas.

The flow of the smoke fluid and the pressurized gas is indicated by the arrows.

The smoke fluid 103 is driven to a mixing unit 110 where it is mixed with the gas. The mixture is guided into a heat exchanger 105 causing the smoke fluid to vaporize and to form a smoke 107 upon contact with the surrounding air when exiting the smoke generator 101. The smoke generator may further comprise a fan (122) at the smoke exit which can be controlled to regulate the airflow from the generator with the smoke. The fan may be omitted. A valve 111 regulates the pressure of the gas 107 before being mixed with the smoke fluid 103. The valve 111 for regulating the pressure may in another embodiment be placed after the mixing of the smoke fluid and the gas.

A pressure sensor 119 is placed in the conduit after the valve 111 detecting the pressure of the gas or of the fluid-gas mixture. The pressure sensor may be placed in the conduit before the mixing unit, i.e. before the mixing of the gas and the smoke fluid. Alternatively, the pressure sensor may be placed in the conduit after the mixing unit after the mixture of the gas and the smoke fluid. The pressure sensor may for example be a resistive pressure sensor, optionally with a capillary tube to restrict the flow to the sensor.

The smoke generator further comprises a control unit 113 connected 115 to the valve 111 and configured to control the valve 111 and thereby regulate the gas pressure. The control unit may for example comprise a microcontroller, a computer, a microprocessor, printed circuit board or the like.

Whereas the airflow of the generated smoke is primarily controlled by adjusting the setting of the fan placed at the exit of the smoke generator, the smoke density or amount of smoke to be generated by the smoke generator (i.e. how ‘heavy’ or thick the smoke is) is primarily controlled by adjusting the amount of smoke fluid supplied to the heat exchanger. This in turn set requirements to the pressure at the entrance to the heat exchanger to ensure the desired continuous flow of smoke fluid through the heat exchanger. The desired amount of smoke to be generated may be based on input 121 from a user and/or based on pre-programmed data.

According to the invention the smoke generator is controlled to set and obtain a certain target pressure to ensure the necessary and sufficient pressure at the entrance to the heat exchanger corresponding to the desired density parameter and thereby to the amount of smoke fluid being used.

This is obtained by the pressure sensor 119 interfacing 117 with the control unit 113, which utilises the pressure as feedback in a closed loop control process for controlling the valve 111. The desired target pressure is determined as a function on the desired amount of smoke to be generated. The actual values may be read from an indexed look-up table within the machine control program. In this way the target pressure at the entrance to the heat exchanger is obtained and kept regardless of the amount of smoke fluid delivered, regardless of the gas pressure supplied to the smoke generator, and completely or at least to some extent irrespective of any fluctuations in the smoke fluid delivery. Also variations in the pressure at the heat exchanger entrance otherwise caused by back pressure in the heat exchanger can be reduced or even avoided.

The input 121 on the desired amount of smoke may be based on an external communication signal e.g., based on a DMX protocol, or the like, or may additionally or alternatively be based on a pre-programmed pattern stored in the control unit.

The control of the valve 111 may be implemented as a standard PI or PID control algorithm. The PI or PID controller calculates an “error” value as the difference between the measured pressure and the desired target pressure or set-point and minimizes the error by the adjustment or regulation of the valve 111.

The valve 111 is preferably a proportional valve such as an Emerson Proportional Valve. The PWM control voltage of the valve may be provided directly by the electronics in the smoke generator.

The pressure changes caused by the fluid entering the heat exchanger can additionally be used to detect the loss of fluid supply and to initiate a shutdown of the machine. The pressure sensor may also be used to detect gas pressure failure, which can then be reported over for example a RDM communication protocol from an integrated DMX controller. However any other communication protocol or communication means can be used.

The controller may be adapted to start a shut-down process of the smoke generator in case of malfunctioning of some part of the system, e.g. an interruption of the external power supply, the delivery of smoke fluid or failure or malfunction of the fluid system or pumps or other components. The controller may then deactivate the fluid supply and optionally activate a purging system such as an air pump to purge the heat exchanger and/or the fluid pump. This prevents progressive build-up of polymerized glycol in the heat exchanger which may otherwise result in premature failure of the system.

In the smoke generating system 200 shown in FIG. 2, the pressurized gas 107 is used as driving means of the smoke fluid 103 for regulating the flow of the smoke fluid. The pressurized gas 107 is guided 221 directly to the container of the smoke fluid 103 optionally through a valve 223 for regulating the gas pressure.

As shown in FIG. 3, the smoke generator 301 may in an embodiment comprise a fluid pump 325 positioned to regulate the flow of the smoke fluid. The fluid pump may for example be a dosage pump or an fluid pump. The fluid pump may be controlled 327 by the control unit 113 or by another control unit. The fluid pump is preferably controlled in accordance with the input 121 on the desired amount of smoke to be generated.

The embodiment of the smoke generating system 400 shown in FIG. 4 corresponds to the smoke generating system 200 of FIG. 2, only here the conduits 221 and the optional valve 223 is positioned inside the smoke generator 400. Hereby the smoke generator 400 is prepared to be connected to a supply of pressurized gas only in one place. Also, the valve 223 may then be controlled 429 by the control unit 113.

FIG. 5 is a flow chart showing an embodiment of the control of the smoke generator including a start-up of the generator in a way to safely open the valve gradually reducing the risk of over-pressurizing the system and increasing the safety of the system. The smoke generator is normally started with a zero smoke fluid flow and the valve 111 closed, 501. In the next step 502 the smoke fluid flow and a target pressure are determined and/or calculated based on an input 121 demand for the desired amount of smoke to be generated (a smoke density parameter). This determination may be performed by the use of stored look-up tables or alternatively from stored functional relationship between the different parameters.

The target pressure is then used to estimate a set point for the valve opening signal (PWM), 503, whereupon the operating cycle of the generator comprising the closed loop feedback control is initiated, 504. Firstly, the pressure error expressing the difference between the target pressure and the measured pressure is calculated, 505. Depending on the size of the error pressure, the control method may branch to either the closed loop regulation or a gradual step-wise regulation of the valve. In case the error is non-zero or larger than some threshold, the valve is regulated by incrementing the PWM signal and the system is allowed time to react for example 0.5 seconds or similar, 506. The valve PWM signal is then compared to a pre-set threshold, 507, which if exceeded indicate a potential error with the gas supply, 508, which may be reacted upon for example by warning signals or by preventing the generator to be started. If the valve signals are within the acceptable, 509, the closed loop regulation of the valve employing for example a standard PI or PID control is performed, 510 and the smoke generator is run, 511.

While preferred embodiments of the invention have been described, it should be understood that the invention is not so limited and modifications may be made without departing from the invention. The scope of the invention is defined by the appended claims, and all devices that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein. 

1-13. (canceled)
 14. A method of controlling a smoke generator, comprising: receiving a smoke density parameter indicative of a desired amount of smoke to be generated by the smoke generator; regulating, via a valve, a pressure of a gas; regulating the flow of the smoke fluid as a function of the smoke density parameter; measuring a gas pressure at a position between the valve and a heat exchanger; controlling the valve as a function of the smoke density parameter and the measured gas pressure; mixing the smoke fluid and the gas to form a mixture; and heating, via the heat exchanger, the mixture to form a smoke.
 15. The method of claim 14, wherein controlling the valve is performed by at least one of a proportional-integral (PI) controller and a proportional-integral-derivative (PID) controller.
 16. The method of claim 14, wherein measuring the gas pressure is performed before the smoke fluid is mixed with the gas.
 17. The method of claim 14, wherein measuring the gas pressure is performed after the smoke fluid is mixed with the gas.
 18. The method of claim 14, further comprising determining the flow of the smoke fluid and regulating the flow of the smoke fluid as a function of the smoke density parameter.
 19. The method of claim 14, further comprising determining the flow of the smoke fluid, and controlling the valve as a function of the smoke density parameter, the flow of the smoke fluid, and the gas pressure.
 20. The method of claim 19, wherein the flow of the smoke fluid is determined by a flow sensor.
 21. The method of claim 14, wherein regulating the flow of the smoke fluid is performed by a dosage pump, and the flow of the smoke fluid is determined by the dosage pump.
 22. The method of claim 14, further comprising determining a temperature of the heat exchanger, and controlling the valve as a function of the temperature of the heat exchanger.
 23. The method of claim 14, further comprising receiving information associated with a type of the smoke fluid, and controlling the valve as a function of the type of the smoke fluid.
 24. The method of claim 14, wherein controlling the valve is performed based on a look-up table that includes target gas pressure values for a plurality of smoke density parameters.
 25. A smoke generator adapted to be connected to a supply of a pressurized gas and a supply of a smoke fluid, the smoke generator comprising: a valve to regulate a pressure of the pressurized gas; a fluid driving means to regulate a flow of the smoke fluid; a mixing unit arranged to mix the smoke fluid and the pressurized gas; a heat exchanger to heat a mixture of the smoke fluid and the pressurized gas to vaporize the smoke fluid and form a smoke upon ejection into surrounding air; a pressure sensor to measure a gas pressure at a position between the valve and the heat exchanger; and a control unit to receive a smoke density parameter indicative of a desired amount of smoke to be generated by the smoke generator, to regulate the flow of the smoke fluid as a function of the smoke density parameter, and to control the valve based on the smoke density parameter and the measured gas pressure.
 26. A smoke generator, comprising: a valve that regulates a pressure of a gas; a pump that regulates a flow of a smoke fluid; a mixing unit that is coupled to the valve and the pump and mixes the gas and the smoke fluid; a heat exchanger that is coupled to the mixing unit and heats a mixture of the gas and the smoke fluid to form a smoke; a pressure sensor that measures a gas pressure at a position between the valve and the heat exchanger; and a control unit that is in communication with the valve and the pump and receives a smoke density parameter, regulates the flow of the smoke fluid based on the smoke density parameter, and controls the valve based on the smoke density parameter and the gas pressure.
 27. The smoke generator of claim 26, further comprising at least one of a proportional-integral (PI) controller and a proportional-integral-derivative (PID) controller to control the valve.
 28. The smoke generator of claim 26, wherein the pressure sensor measures the gas pressure before the smoke fluid is mixed with the gas.
 29. The smoke generator of claim 26, wherein the pressure sensor measures the gas pressure after the smoke fluid is mixed with the gas.
 30. The smoke generator of claim 26, wherein the pump regulates the flow of the smoke fluid as a function of the smoke density parameter.
 31. The smoke generator of claim 26, wherein the valve regulates the pressure of the gas as a function of the smoke density parameter, the flow of the smoke fluid, and the gas pressure.
 32. The smoke generator of claim 26, further comprising a flow sensor to determine the flow of the smoke fluid.
 33. The smoke generator of claim 26, wherein the pump comprises a dosage pump that determines the smoke fluid flow.
 34. The smoke generator of claim 26, wherein the valve regulates the pressure of the gas as a function of a temperature of the heat exchanger.
 35. The smoke generator of claim 26, wherein the valve regulates the pressure of the gas as a function of a type of the smoke fluid.
 36. The smoke generator of claim 26, wherein the valve regulates the pressure of the gas based on a look-up table that includes target gas pressure values for a plurality of smoke density parameters. 